Abstract: The present invention provides methods for predicting the treatment response of a cancer patient, using a tumour copy number profile for the patient. The method comprise analysing the copy number profile to assess whether the characteristics of at least one copy number feature are indicative of the presence of focal amplifications in the tumour genome, wherein the at least one copy number feature is selected from: copy number change-point, segment size and segment copy number. The patient is predicted as being likely to be resistant to treatment with an agent that induces the formation of micronuclei (e.g. doxorubicin) if the characteristics of the at least one copy number features are indicative of the presence of focal amplifications in the tumour genome. Also provided a related methods and systems.